The boiling point of water is 100°C, the boiling point of ethanol is 78°C, and the boiling point of carbon tetrachloride is 76°C. Which describes the strength of the forces between the molecules of water, ethanol, and carbon tetrachloride?

Question

A. The forces between the molecules of water, ethanol, and carbon tetrachloride are very similar.
B. The forces between molecules are greatest for carbon tetrachloride and ethanol molecules but much lower for water molecules.
C. The forces between water molecules are greater than those between ethanol and carbon tetrachloride molecules.
D. The forces between them are not a good predictor of boiling points of different substances.

Answer 1

The correct answer is C. The forces between water molecules are greater than those between ethanol and carbon tetrachloride molecules.

Water molecules exhibit strong hydrogen bonding due to the presence of highly polar O-H bonds, which results in a higher boiling point compared to ethanol (which has weaker hydrogen bonding) and carbon tetrachloride (which primarily has Van der Waals forces). Thus, the intermolecular forces in water are stronger, leading to a higher boiling point.